Abstract
PurposeTo describe a new stereotest in the form of a game on an autostereoscopic tablet computer designed to be suitable for use in the eye clinic and present data on its reliability and the distribution of stereo thresholds in adults.MethodsTest stimuli were four dynamic random-dot stereograms, one of which contained a disparate target. Feedback was given after each trial presentation. A Bayesian adaptive staircase adjusted target disparity. Threshold was estimated from the mean of the posterior distribution after 20 responses. Viewing distance was monitored via a forehead sticker viewed by the tablet's front camera, and screen parallax was adjusted dynamically so as to achieve the desired retinal disparity.ResultsThe tablet must be viewed at a distance of greater than ∼35 cm to produce a good depth percept. Log thresholds were roughly normally distributed with a mean of 1.75 log10 arcsec = 56 arcsec and SD of 0.34 log10 arcsec = a factor of 2.2. The standard deviation agrees with previous studies, but ASTEROID thresholds are approximately 1.5 times higher than a similar stereotest on stereoscopic 3D TV or on Randot Preschool stereotests. Pearson correlation between successive tests in same observer was 0.80. Bland-Altman 95% limits of reliability were ±0.64 log10 arcsec = a factor of 4.3, corresponding to an SD of 0.32 log10 arcsec on individual threshold estimates. This is similar to other stereotests and close to the statistical limit for 20 responses.ConclusionsASTEROID is reliable, easy, and portable and thus well-suited for clinical stereoacuity measurements.Translational RelevanceNew 3D digital technology means that research-quality psychophysical measurement of stereoacuity is now feasible in the clinic.
Highlights
Stereopsis is the most demanding binocular visual function because it requires good vision in both eyes, good oculomotor control, and the requisite cortical mechanisms to extract depth information
We give a complete description of the ASTEROID stereotest and present numerical simulations justifying our design decisions. We compare it against a laboratory psychophysics version of the test presented on a stereoscopic 3D television and against the Randot Preschool stereotest, and we present the distribution of results obtained in a nonclinical adult population
The sweat factor or sweet point is the stimulus strength that minimizes the variability of the psychometric function for a given number of trials.[36,37,38]
Summary
Stereopsis is the most demanding binocular visual function because it requires good vision in both eyes, good oculomotor control, and the requisite cortical mechanisms to extract depth information. Measurement of stereoacuity is the gold standard clinically for diagnosing the presence and quality of binocular vision.[1] Several clinical stereotests exist, including the Randot, Randot Preschool, Frisby, TNO, Titmus, and Lang stereotests.[2,3] All of these share certain disadvantages: (1) consisting of cards or plates, they offer only a number of discrete levels; (2) they admit monocular cues, especially if the head is moved or tilted[4,5]; (3) there is a nonnegligible. For many decades it has been standard to use computers to present arbitrary stimuli, run adaptive techniques such as Bayesian staircases, and/or fit psychometric functions to data.[6,7,8,9] For these reasons, over the last few years several groups have proposed computerized stereotests that aim to bring laboratory-quality psychophysics to the clinic
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